A light emitting diode (LED) is a p-n junction diode having characteristics of converting electric energy into light energy, may be configured with a compound semiconductor of Group III and Group V elements or the like of the periodic table and may represent various colors by adjusting a composition ratio of a compound semiconductor.
When a forward voltage is applied to the light emitting diode, electrons of n layer and holes of p layer are coupled and emit energy corresponding to an energy gap between a conduction band and a valance band. When the energy is converted to light, the light emitting diode emits the light.
Nitride semiconductors are attracting a great attention in the development fields of optical devices and high power electronic devices due to high thermal stability and wide band-gap energy thereof. In particular, blue light emitting diodes, green light emitting diodes, and ultraviolet (UV) light emitting diodes using the nitride semiconductors are commercially available and widely used.
Meanwhile, a carrier over-shooting occurs in an active layer where the electrons of the n layer and the holes of the p layer are coupled to each other, which may have an influence on a decrease in internal quantum efficiency.
The carrier over-shooting or a carrier overflight means that the energy of the electrons to be injected into the active layer is high and is not injected into a quantum well, and thus the internal quantum efficiency may be reduced.
In order to capture more carriers in the active layer and to prevent the carrier over-shooting, a new structure capable of improving the internal quantum efficiency is required to be developed.